Downloaded 52 times
More Related Content
Similar to Clostridium tetani
Clostridium tetani
- 2. CLOSTRIDIUM TETANI Dr VS Vatkar Asso Prof Microbiology Department D Y Patil Medical College, Kolhapur
- 3. Causative organismof tetanus Known since early time, described by Hippocrates & Aretaeus. Kitasato (1889): isolated it in pure culture and reproduced the disease in animals Widely distributed in soil and in intestine of animals & humans Other sources: street & hospital dust, cotton wool, plaster of Paris, bandages, catgut, talc, wall plaster, clothing etc
- 4. MORPHOLOGY Gram +ve,slender bacilli 4-8 by 0.5 µm size Arranged singly or in chains Spore bearing, spherical, terminal & bulging (drum stick appearance) Non-capsulated, motile- peritrichate flagella
- 5. CULTURAL CHARACTERISTICS Obligateanaerobes Opt temp: 37o C, pH- 7.4 Grows on ordinary media Blood agar: swarming, α hemolysis Deep agar shake culture: fluffy balls Gelatine stab culture: fir tree type growth with liquefaction RCM: turbidity, gas formation, meat pieces turns black
- 6.
- 7. BIOCHEMICAL REACTIONS Indol+ve MR – VP: negative H2S: not formed Feeble proteolytic Does not ferment sugars
- 8. RESISTANCE Spores :more resistant to heat Killed by boiling 10-15 min, but some may resist boiling up to 3 hrs Autoclaving 121 0 C for 20 min : recommended Survive in soil: years & resistant to most antiseptics Not destroyed by 5% phenol, 0.1% mercuric chloride Iodine 1%, H2O2 kill spores within few hours
- 9. CLASSIFICATION 10 serologicaltypes: based on agglutination (type I – X) Type IV : non flagellated strain All types produce same type of toxin & is neutralized by anti toxin produced against any one type TOXINS: Hemolysin (Tetanolysin) & a powerful neurotoxin: Tetanospasmin
- 10. Tetanolysin: heatlabile, oxygen labile, no relevant role in pathogenesis of tetanus TETANOSPASMIN: toxin responsible for tetanus, oxygen stable, plasmid coded, Inactivated by heat at 65 0 C for 5 min Toxoided spontaneously or in presence of low conc formaldehyde
- 11. TETANOSPASMIN Good antigenic,neutralizes with specific anti toxin Simple protein, made up of single polypeptide chain Heterodimer consist of : heavy chain, light chain joined by disulphide bond MLD: for human, 130 nanograms Horse : more susceptible, guinea pigs, mice, goats & rabbits : in descending order, birds & reptiles: more resistant.
- 12. PATHOGENESIS Little invasivepower Washed spores : injected in experimental animals do not germinate & destroyed by phagocytosis Germination & toxin production occur only in favourable conditions like reduced OR potential, devitalized tissues, foreign bodies or concurrent infection Toxin: mainly absorbed by motor nerve endings & transported to CNS
- 13. MECHANISM OF ACTION Resembles like strychnine Blocks synaptic inhibition of spinal cord (inhibitory terminals that uses glycine & GABA as neurotransmitters. Toxin acts pre synaptically (Strychnine acts post synaptically) Abolition of spinal inhibition causes uncontrolled spread of impulse initiated anywhere in CNS Causes muscle rigidity & spasm (due to simultaneous contraction of agonist & antagonist muscles, in absence of inhibition)
- 14. Tetanus toxin blockssynaptic inhibition At inhibitory terminals that use GLYCINE & GABA neurotransmitters Toxin acts pre synaptically Abolition of spinal inhibition Uncontrolled spread of impulses Initiated anywhere in CNS Muscle rigidity & spasms due to Simultaneous contraction of agonist & antagonist, absence of inhibitory responce
- 17. TETANUS Tonic muscularspasm Followed by injury, especially puncture wounds Rarely followed by surgery Sometimes may be due to suppurative foci like otitis media Septic abortion Unhygienic practices; application of cow dung on umbilical cord Unsterile injections
- 18. Incubation period:variable, 2 days – several weeks (6-12 days) Site & nature of wound Dose & toxigenesity of organism Immune status of the patient I P: short : prognosis: grave High mortality rate, 80-90% Tetanus neonatorum & uterine tetanus : high fatality rate
- 19. Common indeveloping countries: warm climate, rural areas: soil ,fertile & highly cultivated Unhygienic practices Universal immunization of infants & expected mothers: reduced incidence of tetanus, especially in rural areas
- 22. LABORATORY DIAGNOSIS Alwayson clinical ground Lab tests: help for confirmation MICROSCOPY: unreliable, demonstration of drumstick bacilli in the wound itself is not diagnostic, Cl tetani, Cl tetanomorphum, Cl sphenoides : morphologically similar CULTURE: diagnostic, specimen should be from the deeper part of the wound. Plated on blood agar, incubated anaerobically, swarming seen
- 23. CULTURE Material :also inoculated into 3 bottles of RCM 1st bottle: heated to 80 0 C for 15min 2nd bottle: heated to 80 0 C for 5 min 3rd bottle: kept unheated Purpose of heating for different period : to kill vegetative bacteria, undamaged tetanus spores which may be heat resistant Bottles : incubated at 37 0 C & subcultured on blood agar plate daily for next 4 days Polymyxin B blood agar : selective medium
- 24. IN VITRO TOXIGENECITYTESTING Blood agar containing 4% agar: tetanus antitoxin (1500 Units/ml): spared on 1/2 plate & test strain is inoculated on both halves, incubated anaerobically for 2 days. Toxigenic Cl.tetani : hemolysis around colonies on half plate without antitoxin & no hemolysis on half : plated with antitoxin
- 25. IN VIVO TOXIGENECITYTEST Tested in animals: 2 mice 2-4 days old cooked meat culture (0.2 ml) is injected in root of tail of both mice One mouse is protected with tetanus antitoxin (1000 units) , other is unprotected Symptoms develop within 12-24 hrs, begins with stiffness of tail, rigidity to leg on inoculated side then opposite leg, trunk & forelimb (ascending tetanus) Animal dies within 2 days
- 26. PROPHYLAXIS Surgical prophylaxis:remove the foreign body, necrotic tissue, blood clot to prevent anaerobic environment Radical excision: depending on the type of wound Antibiotics : inhibit pyogenic bacteria & tetanus bacilli Long lasting Penicillin : drug of choice Erythromycin : 500 mg b d for 5 days Bacitracin / neomycin : applied locally
- 27. IMMUNIZATION Passive immunization: Tetanus antitoxin: injections Anti tetanus serum (ATS): prepared from hyperimmune horse, 1500 units s/c or i/m , given to non immune person after injury Reduces incidence & prolongs incubation period of tetanus Two disadvantages: heterologus serum: immune elimination & hypersensitivity
- 28. Half lifeof ATS: 7 days but in previously received person: eliminates quickly (combines with previously existing antibodies) Hypersensitivity: mild local reaction to serum sickness sometimes fatal anaphylaxis Human antitetanus immunoglobulins (TIG): small doses,250 units, longer half life(3-5 weeks), prepared from immunization human volunteers, availability limited
- 29. ACTIVE IMMUNIZATION Toxoidedform : plain toxoid or adsorbed on aluminium hydroxide or phosphate Adsorbed toxoid : more antigenic Given along with diphtheria & pertussis (DPT vaccine) as triple vaccine Deep i/m at an interval of 4-6 weeks, first 2 doses, starting at the age of 1 & ½ month, 3rd dose after 6 month or recommended in immunization schedule
- 30. Booster dose:10 yrs Too frequent inj of T T should be avoided: hypersensitivity reactions may occur occasionally COMBINED IMMUNIZATION: given to non immunized person TIG inj at one site & first dose of TT 2nd & 3rd dose of TT at interval of 1 month
- 31. TREATMENT Quite environment Controlling spasm: sedatives, muscle relaxtants Maintain airway: tracheostomy, +ve pressure ventilation Human TIG 10,000 IU, slow IV infusion, if needed repeat 5000 IU later Antibiotics: penicillin, metronidazole for wk Patient recover from tetanus : give full course of TT(active immunization)